1. Field of the Invention
The present invention relates to an outer shuttle of a sewing machine, having a structure such that the outer shuttle accommodates an inner shuttle that grabs an upper thread and accommodates a bobbin around which a lower thread is wound, and a gear shaft having a driven gear connected to a driving gear provided on a lower shaft of a driving source that is rotatably supported in the sewing machine is fixed by press-fitting to a shuttle body.
2. Description of the Related Art
General sewing machines are provided with a shuttle device including an outer shuttle having a cutting edge for grabbing an upper thread and an inner shuttle that accommodates a bobbin around which a lower thread is wound in order to form stitches using the upper thread and the lower thread wound around the bobbin. A gear shaft is attached to a lower end surface of the outer shuttle, and the outer shuttle is rotated by a driving gear that is attached to a lower shaft of the sewing machine to engage with the gear shaft. An outer shuttle in which the shuttle body and the gear shaft are formed of separate members is known. An outer shuttle of this type is disclosed in Japanese Utility Model Registration No. 3054640, for example.
The shuttle body and the gear shaft are formed of separate members when the two members are formed of different materials and it is difficult to form the same integrally. This is the case where the shuttle body is formed of metal and the gear shaft is formed of a synthetic resin, for example. When constituent elements of a shuttle are formed of separate members and different materials, the manufacturing cost may be decreased. Thus, a shuttle device of a type such that the shuttle body and the gear shaft are formed of separate members may be used depending on the grade of a sewing machine. FIGS. 4A and 4B are schematic views for describing the outer shuttle disclosed in Japanese Utility Model Registration No. 3054640.